1. Field of the Invention
The invention is a catalytic process for converting crude petroleum fractions to gasoline. More particularly the invention is a process for converting a heavy naphtha fraction by hydrocracking to improve the octane and reduce the volume of heavy end.
2. Description of Related Methods in the Field
In the refining of petroleum derived hydrocarbon oils, it is often desirable to subject the hydrocarbon oil to catalytic hydroprocessing in order to improve the suitability of the oil as a liquid fuel. Hydrocracking is a relatively severe hydroprocessing in which a petroleum distillate oil is passed together with hydrogen through a bed of catalyst which has specific activity for cracking relatively high molecular weight hydrocarbon oils to a lower molecular weight.
The molecular weight is selected to produce a boiling range in the liquid fuel boiling range. Such catalysts also have hydrogenation activity. Hydrogenation activity includes removal of unsaturation, organosulfur and organonitrogen. Unsaturation is converted to a more color stable saturation. Organosulfur and organonitrogen are converted to gaseous hydrogen sulfide and ammonia which are removed in a gas-liquid separator. Hydrocracking is used advantageously to convert petroleum distillate oil to relatively sulfur-free, nitrogen-free, color stable products such as gasoline, jet fuel and diesel fuel.
U.S. Pat. No. 5,318,689 to H. Hsing and R. E. Pratt discloses a process for converting heavy naphtha. The process utilizes fractionation to produce heavy naphtha and fluid catalytic cracking (FCC) to yield cracked naphtha and a C.sub.3 to C.sub.5 olefin fraction.
U.S. Pat. No. 3,758,628 to J. C. Strickland et al. discloses a process for converting low octane paraffinic naphtha to high octane gasoline. The process utilizes hydrocracking, alkylation, fluid catalytic cracking (FCC), catalytic reforming and solvent extraction.